Kinetics of the gas-phase reaction between iodine and trimethylsilane and the bond dissociation energy D(Me3Si—H)

Abstract

The title reaction has been investigated in the temperature range 519–618 K. The only products, formed in equal quantities, were trimethylsilyl iodide and hydrogen iodide, Rates were found to be surface sensitive below about 560 K, but not so in the range 567–618 K where the rate law [graphic omitted] was obeyed over a wide range of iodine and Me₃SiH pressures. This expression is consistent with an iodine atom abstraction mechanism and for the step. I˙+ Me₃SiH → Me₃Si˙+ HI, log (k₁/dm³ mol^–1 s^–1)= 10.9 – 82.3 kJ mol^–1/RT 1n 10 has been deduced. From this the bond dissociation energy D(Me₃Si—H)=(376 ± 11) kJ mol^–1(90 kcal mol^–1) is obtained. The implications of this value for the pyrolyses of organosilanes are discussed.